TWI608132B - Method of electroplating photoresist defined features from copper electroplating baths containing reaction products of pyridyl alkylamines and bisepoxides - Google Patents

Description

Method for characterizing a copper electroplating bath electroplating photoresist from a reaction product containing a pyridylalkylamine and a bisepoxide

The present invention is directed to a method of characterizing a copper electroplating bath electroplating photoresist from a reaction product comprising a pyridylalkylamine and a bisepoxide. More particularly, the present invention relates to a method of defining a feature of a copper electroplating bath electroplating photoresist comprising a reaction product comprising a pyridylalkylamine and a bisepoxide, wherein the photoresist is characterized It has a substantially uniform surface morphology.

Photoresist-defined features include copper pillars and redistribution layer wiring, such as bond pads and line space features of integrated circuit wafers and printed circuit boards. The features are formed by a lithography method in which a photoresist is applied to a substrate (such as a semiconductor wafer wafer, commonly referred to in the packaging art as a die, or an epoxy/glass printed circuit board). Typically, a photoresist is applied to the surface of the substrate and a patterned mask is applied to the photoresist. The masked substrate is exposed to radiation such as UV light. Typically, a portion of the photoresist that is exposed to radiation is developed Remove or remove to expose the surface of the substrate. Depending on the particular pattern of the mask, the outline of the circuit trace or aperture may be formed with an unexposed photoresist left on the substrate to form a sidewall of the circuit trace or aperture. The surface of the substrate comprises a metal seed layer or other conductive metal or metal alloy material that enables the surface of the substrate to conduct electricity. The substrate with the patterned photoresist is then immersed in a metal plating bath (typically, a copper plating bath) and the metal is plated in a circuit trace or aperture to form features such as pillars, bonds A pad or circuit line, that is, a line space feature. When the plating is completed, the remaining portion of the photoresist is stripped from the substrate with a lift-off solution, and the substrate having the characteristics defined by the photoresist is further processed.

A post, such as a copper post, is typically covered with solder to effect adhesion and conductance between the semiconductor wafer of the plated post and the substrate. The arrangement is found in advanced packaging technology. Due to the improved input/output (I/O) density, the solder-covered copper pillar structure is a fast growing segment in advanced packaging applications compared to individual solder bumps. Copper stud bumps with non-returnable copper posts and reflowable solder caps have the following advantages: (1) copper has low resistance and high current density capability; (2) copper thermal conductivity provides more than three times solder bump thermal conductivity Rate; (3) can improve the traditional BGA CTE (spherical grid array thermal expansion coefficient) mismatch problem that may cause reliability problems; and (4) the copper column does not collapse during reflow, allowing very fine pitch without damaging the standoff height.

Among all copper pillar bump manufacturing methods, electroplating is by far the most commercially viable method. In actual industrial production, electroplating provides large-scale productivity in consideration of cost and process conditions, and there is no polishing or etching process to change the surface morphology of the copper post after forming the copper pillar. Therefore, it is especially important to obtain a smooth surface morphology by electroplating. Used for electroplating copper columns Ideal copper plating chemistries and methods produce deposits with excellent uniformity, flat pillar shapes, and void-free intermetallic interfaces after solder reflow, and can be plated at high deposition rates to achieve high wafer throughput. However, the development of such plating chemistries and methods is a problem in the industry, as an improvement in one property typically comes at the expense of another. Copper-based structures have been used by consumer manufacturers for consumer products such as smart phones and PCs. As wafer level processing (WLP) continues to evolve and copper pillar technology is employed, there is an increasing demand for advanced copper plating baths and methods that can produce reliable copper pillar structures.

Similar morphological problems are also encountered with metal plated redistribution layer wiring. Formal defects in combination with liner and line space features also compromise the effectiveness of advanced packaged articles. Accordingly, there is a need for copper plating methods and chemicals that provide features that are characterized by copper photoresists having features that have a substantially uniform surface morphology.

The present invention relates to a method for electroplating a photoresist-defining feature comprising: a) providing a substrate comprising a photoresist layer, wherein the photoresist layer comprises a plurality of apertures; b) providing copper plating a bathing bath comprising one or more reaction products of one or more pyridylalkylamines and one or more diepoxides; an electrolyte; one or more accelerators; and one or more inhibitors; Substituting said substrate comprising said photoresist layer having said plurality of apertures in said copper electroplating bath; and d) plating a plurality of copper photoresists in said plurality of apertures By a defined feature, the plurality of photoresists define a feature comprising an average TIR% of from -5% to +12%.

The copper plating bath contains one or more pyridylalkylamines and a reaction product of one or more diepoxides, an electrolyte, one or more sources of copper ions, one or more accelerators, and one or more inhibitors in an amount sufficient to electroplate copper light having an average TIR% of from -5% to +12% The characteristics of the resist definition.

The invention also relates to an array of photoresist-defined features on a substrate comprising an average TIR% of from -5% to +12% and a WID% of from 5% to 14%.

The electroplating method and bath provide features that are defined by a photoresist having a substantially uniform morphology and substantially free of nodules. The post and the bond pad have a substantially flat profile. The copper electroplating bath and method are capable of achieving an average TIR% to achieve the desired morphology.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a SEM of a copper column at 300X electroplated from a copper electroplating bath containing the reaction product of 2-(2-aminoethyl)pyridine and 1,4-butanediol diglycidyl ether.

Figure 2 is a copper column electroplated at 300X from a copper electroplating bath containing a reaction product of 2-(2-aminoethyl)pyridine and 1,2,7,8-dicyclooxyoctane. SEM.

Figure 3 is a conventional leveling compound containing a reaction product as 2-methylquinolin-4-amine, 2-(2-aminoethyl)pyridine and 1,4-butanediol diglycidyl ether. The copper electroplating bath was electroplated with a SEM of a copper column at 300X.

Unless the context clearly indicates otherwise, the following abbreviations as used throughout this specification shall have the following meanings: A = amperes; A / dm ² = amperes / square decimeters = ASD; ° C = degrees Celsius; UV = ultraviolet radiation; g=gram; ppm= parts per million=mg/L; L=liter, μm=micron=micrometer; mm=mm; cm=cm; DI=deionized;mL=ml; mol= Mohr; mmol = millimolar; Mw = weight average molecular weight; Mn = number average molecular weight; SEM = scanning electron microscope; FIB = focused ion beam; WID = intragranular; TIR = total indicator deviation = total indicator reading = full indicator movement = FIM; RDL = redistribution layer; and Avg. = average.

As used throughout this specification, the term "plating" refers to metal plating. "Deposition" and "plating" are used interchangeably throughout this specification. "Accelerator" means an organic additive that increases the plating rate of the plating bath. "Inhibitor" means an organic additive that inhibits the rate of metal plating during electroplating. The term "array" means an orderly arrangement. The term "portion" means a moiety or a portion of a polymer that may comprise an entire functional group or a portion of a functional group. The terms "part" and "group" are used interchangeably throughout this specification. The term "aperture" means an opening, a hole or a gap. The term "morphology" means the form, shape and structure of an object. The term "total indicator deviation" or "total indicator reading" is the difference between the maximum and minimum measurements (ie, the reading of the indicator) on the planar, cylindrical or wavy surface of the part. It is the amount of deviation from flatness, roundness (circularity), cylindricity, concentricity with other cylindrical features or similar conditions. The term "profilometry" means the use of technology in measuring and dissecting objects or the projection of a laser or white light computer to perform surface measurements of a three-dimensional object. The term "pitch" means the frequency at which features on a substrate are positioned relative to one another. The term "normalized" means used to obtain a re-scaling with respect to the value of the dimensional variable, such as in the form of TIR%. The term "average" means the value that represents the center or typical value of a parameter. The term "parameter" means forming a group that defines a system or sets its operating conditions. A value or other measurable factor. The article "a" is used to mean both singular and plural.

All numerical ranges are inclusive and can be combined in any order, but it is obvious that such numerical ranges are limited to a total of 100%.

The method and bath of the present invention for defining features of an electroplated copper photoresist can achieve an array of features defined by photoresist having an average TIR% such that the features are substantially smooth, free of nodules and are in the column The combination of the liner and the line space feature has a substantially flat profile. The photoresist of the present invention defines features that are plated with a photoresist remaining on the substrate and extend beyond the plane of the substrate. This is in contrast to dual damascene and printed circuit board plating, which typically do not use a photoresist to define features that extend beyond the plane of the substrate but are inlaid into the substrate. An important difference between the features defined by the photoresist and the features of the damascene and printed circuit board is that the plated surface comprising the sidewalls is electrically conductive relative to the damascene and printed circuit board. The dual inlay and printed circuit board plating bath has a bath formulation that provides a bottom-up or super-conformal fill, and the bottom of the feature is plated faster than the top of the feature. In the characteristics defined by the photoresist, the sidewalls are non-conductive photoresists, and the plating is performed only at the bottom of the features having the conductive seed layer, and is deposited in a conformal or uniform plating rate everywhere.

While the present invention is generally directed to a method of electroplating a copper pillar having a circular morphology, the present invention is also applicable to other photoresist-defined features, such as bond pads and line space features. Generally, in addition to a circular or cylindrical shape, the shape of the feature may be, for example, a rectangle, an octagon, and a rectangle. The method of the present invention is preferably used to electroplate copper-clad cylindrical columns.

The copper plating method provides an array of features defined by copper photoresist, such as copper pillars, and has an average TIR% of from -5% to +12%, preferably -3% to +10%.

In general, the average TIR% of the array of features defined by the photoresist on the substrate involves determining the TIR% of individual features from the feature array on a single substrate and averaging them. Typically, the average TIR% is determined by determining the TIR% of the individual features of the low density or larger pitch regions on the substrate and the TIR% of the individual features of the high density or smaller pitch regions and determining the average of the values. . By measuring the TIR% of a plurality of individual features, the average TIR% becomes representative of the entire substrate.

TIR% can be determined by the following equation: TIR% = [height _center - height _edge ] / height _max × 100

The height _center is the height of the column as measured along its _central axis, and the height _edge is the height of the column as measured along its edge at the highest point on the edge. The height _max is the height from the bottom of the column to the highest point on its top. The height _max is a normalization factor.

The individual characteristic TIR can be determined using the following equation: TIR = height _center -height _edge , where the height _center and height _edge are as defined above.

In addition, the copper plating process and bath can provide an array of features defined by copper photoresists having a WID% of 5% to 14%, preferably 5% to 9%. WID% or grain can be determined by the following equation: WID% = 1/2 × [(height _max - height _min ) / height _avg ] × 100

The height _max is the height of the highest column of the column array plated on the substrate, as measured at the highest portion of the column. The height _min is the height of the shortest column of the column array plated on the substrate, as measured at the highest portion of the column. The height _avg is the average height of all the columns plated on the substrate.

Most preferably, the method of the present invention provides an array of features defined by the photoresist on the substrate, wherein there is a balance between the average TIR% and WID%, such that The TIR% is in the range of -5% to +12%, and the WID% is in the range of 5% to 14%, with a preferred range as disclosed above.

Parameters for determining the TIR, TIR%, and WID% columns can be measured using optical profilometry, such as with white light LEICA DCM 3D or similar devices. Parameters such as column height and spacing can be measured using such devices.

Typically, the copper pillars plated from the copper electroplating bath may have an aspect ratio of from 3:1 to 1:1 or such as from 2:1 to 1:1. The RDL type structure can have an aspect ratio as large as 1:20 (height: width).

The substrate includes, but is not limited to, a semiconductor wafer or die, a reconstructed wafer from an epoxy molding compound (EMC) and an organic laminate.

Preferably, the pyridylalkylamine comprises a compound having the formula:

Wherein R ₁ , R ₂ , R ₃ , R ₄ and R _{5 are} independently selected from hydrogen, (C ₁ -C ₆ )alkyl, (C ₁ -C ₆ )alkyl (C ₆ -C ₁₀ )aryl, -NR ₆ R ₇ and R ₈ -NR ₆ R ₇ , wherein the restriction condition is that at least one of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ is R ₈ -NR ₆ R ₇ ; R ₈ is (C ₁ - C ₁₀ )hydrocarbyl; R ₆ and R _{7 are} independently selected from hydrogen, (C ₁ -C ₆ )alkyl, (C ₆ -C ₁₀ )aryl, (C ₁ -C ₆ )alkyl (C ₆ -C ₁₀ ) aryl. Preferably, R ₁ is R ₈ -NR ₆ R ₇ , R ₈ is a (C ₁ -C ₃ )hydrocarbyl group, and R ₆ and R _{7 are} independently selected from hydrogen, (C ₁ -C ₃ )alkyl and C ₁ -C ₃ )alkyl (C ₆ -C ₁₀ ) aryl. More preferably, R ₁ is R ₈ -NR ₆ R ₇ , R ₈ is a (C ₁ -C ₃ )hydrocarbyl group, and R ₆ and R _{7 are} independently selected from hydrogen, (C ₁ -C ₃ )alkyl and (C) ₁ -C ₃ )alkylphenyl, and R ₂ -R _{5 are} independently selected from hydrogen and (C ₁ -C ₆ )alkyl. Even more preferably, R ₁ is R ₈ -NR ₆ R ₇ , R ₈ is a (C ₁ -C ₃ )hydrocarbyl group, and R ₆ and R _{7 are} independently selected from hydrogen, (C ₁ -C ₂ )alkyl and C ₁ -C ₂ )alkylphenyl, and R ₂ -R ₅ are hydrogen. Most preferably, R ₁ is R ₈ -NR ₆ R ₇ , R ₈ is ethyl, R ₆ and R _{7 are} independently selected from hydrogen and methyl, and R ₂ -R ₅ are hydrogen. Examples of the aforementioned compounds are 2-(2-aminoethyl)pyridine, 2-(2-methylaminoethyl)pyridine and 2-benzylaminoamidopyridine.

Preferably, the diepoxide compound comprises a compound having the formula:

Wherein R ₉ and R _{10 are} independently selected from hydrogen and (C ₁ -C ₄ )alkyl, A=O((CR ₁₁ R ₁₂ ) _m O) _n or (CH ₂ ) _y , each R ₁₁ and R ₁₂ Independently selected from hydrogen, methyl or hydroxy, m = 1-6, n = 1-20 and y =0-6. R ₉ and R _{10 are} preferably independently selected from hydrogen and (C ₁ -C ₂ )alkyl. More preferably, both R ₉ and R ₁₀ are hydrogen. Preferably, m = 2-4. Preferably, n = 1-10, more preferably, n =1. Preferably, y = 0-4, and more preferably 1-4. When A = (CH ₂ ) _y and y =0, then A is a chemical bond.

The bisepoxide of A=O((CR ₁₁ R ₁₂ ) _m O) _n has the formula:

Wherein R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , m and n are as defined above. Preferably, R ₉ and R ₁₀ are hydrogen. Preferably, R ₁₁ and R ₁₂ may be the same or different and are selected from the group consisting of hydrogen, methyl and hydroxy. More preferably, R ₁₁ is hydrogen and R ₁₂ is hydrogen or hydroxy, and when R ₁₂ is hydroxy and m is 2-4, preferably, only one of R ₁₂ is a hydroxy group, and the remainder is hydrogen. Preferably, m is an integer from 2 to 4 and n is an integer from 1 to 2. More preferably, m is 3-4 and n is 1. When m = 4 and n = 1, it is preferred that R ₁₁ and R ₁₂ are hydrogen.

The compound of formula (II) includes, but is not limited to, 1,4-butanediol II Glycidyl ether, ethylene glycol diglycidyl ether, di(ethylene glycol) diglycidyl ether, 1,2,7,8-dicyclooxyoctane, 1,2,5,6-diepoxy Hexane, 1,2,7,8-dicyclooxyoctane, 1,3-butanediol diglycidyl ether, glycerol diglycidyl ether, neopentyl glycol diglycidyl ether, propylene glycol condensed water A glyceryl ether, a di(propylene glycol) diglycidyl ether, a poly(ethylene glycol) diglycidyl ether compound, and a poly(propylene glycol) diglycidyl ether compound.

Compounds specific to formula (III) include, but are not limited to, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, di(ethylene glycol) diglycidyl ether, 1,3-butyl Glycol diglycidyl ether, glycerol diglycidyl ether, neopentyl glycol diglycidyl ether, propylene glycol diglycidyl ether, di(propylene glycol) diglycidyl ether, poly(ethylene glycol) diglycidyl ether compound And poly(propylene glycol) diglycidyl ether compounds.

Other preferred diepoxides include diepoxides having a ring carbon moiety, such as a diepoxide having a six carbon ring moiety. The diepoxides include, but are not limited to, 1,4-cyclohexanedimethanol diglycidyl ether and resorcinol diglycidyl ether.

The reaction products of the present invention can be prepared by a variety of methods known in the art. Typically, one or more pyridylalkylamine compounds are dissolved in DI water and heated to 70 °C - 80 °C, and then one or more diepoxides are added dropwise. The temperature of the heating bath is then increased to about 90 °C. Heat with stirring for 2-4 hours. The temperature of the heating bath is then lowered to room temperature with stirring for an additional 4-8 hours. The amount of each component may vary, but usually a sufficient amount of each of the reactants is added to obtain a molar ratio of a portion from the pyridylalkylamine to a moiety derived from the diepoxide in the 1:3 to 3:1 ratio. Within the range, preferably from 1:2 to 2:1 and optimally from 0.8:1 to 1:0.8.

Suitable copper ion sources are copper salts and include, but are not limited to: copper sulfate; copper halides such as copper chloride; copper acetate; copper nitrate; copper tetrafluoroborate; copper alkyl sulfonate; copper aryl sulfonate; Copper sulfonate; copper perchlorate and copper gluconate. An exemplary copper alkane sulfonate comprises copper (C ₁ -C ₆ ) alkane sulfonate, and more preferably copper (C ₁ -C ₃ ) alkane sulfonate. Preferred copper alkane sulfonates are copper methane sulfonate, copper ethane sulfonate and copper propane sulfonate. Exemplary copper aryl sulfonates include, but are not limited to, copper benzene sulfonate and copper p-toluene sulfonate. A copper ion source mixture can be used. One or more salts of metal ions other than copper ions may be added to the plating bath of the present invention. Preferably, the copper salt is present in an amount sufficient to provide a copper ion amount of from 30 to 60 g/L of the plating solution. More preferably, the amount of copper ions is 40 to 50 g/L.

Electrolytes suitable for use in the present invention may be basic or acidic. Preferably, the electrolyte is acidic. Preferably, the pH of the electrolyte 2. Suitable acidic electrolytes include, but are not limited to, sulfuric acid, acetic acid, fluoroboric acid, alkanesulfonic acids (such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and trifluoromethanesulfonic acid), arylsulfonic acids (such as benzenesulfonate). Acid, p-toluenesulfonic acid), aminosulfonic acid, hydrochloric acid, hydrobromic acid, perchloric acid, nitric acid, chromic acid and phosphoric acid. A mixture of acids can be advantageously used in the metal plating bath of the present invention. Preferred acids include sulfuric acid, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, hydrochloric acid, and mixtures thereof. The acid may be present in the range of from 1 to 400 g/L. Electrolytes are generally available from a variety of sources and can be used without further purification.

The electrolyte may optionally contain a source of halide ions. Chloride or bromide ions are typically used. Exemplary sources of chloride ions include copper chloride, tin chloride, sodium chloride, potassium chloride, and hydrochloric acid. Examples of sources of bromide ions include sodium bromide, potassium bromide, and hydrobromic acid. A wide range of halide ion concentrations can be used in the present invention. Typically, the halide ion concentration is in the range of 0 to 100 ppm, based on the plating bath. It is preferably from 50 ppm to 80 ppm. Such halide ion sources are generally commercially available and can be used without further purification.

The plating composition typically contains an accelerator. Any accelerator (also known as a brightener) is suitable for use in the present invention. Such accelerators are well known to those skilled in the art. Accelerators include, but are not limited to, N,N-dimethyl-dithiocarbamic acid-(3-sulfopropyl) ester; 3-mercapto-propylsulfonic acid-(3-sulfopropyl) ester; Sodium 3-mercapto-propyl sulfonate; dithio-O-ethyl ester-S-ester and potassium 3-mercapto-1-propane sulfonate; bissulfopropyl disulfide; bis-(sodium sulfonate) Propyl)-disulfide; sodium 3-(benzothiazolyl-S-thio)propyl sulfonate; pyridinium propyl sulfobetaine; 1-sodium-3-mercaptopropane-1-sulfonic acid Ester; N,N-dimethyl-dithiocarbamic acid-(3-sulfoethyl) ester; 3-mercapto-ethyl-(3-sulfoethyl) propyl sulfonate; 3-mercapto- Sodium ethyl sulfonate; potassium disulfide-O-ethyl ester-S-ester and potassium 3-mercapto-1-ethanesulfonate; bissulfoethyl disulfide; 3-(benzothiazolyl) -S-thio)ethylsulfonic acid sodium salt; pyridinium ethylsulfobetaine; and 1-sodium-3-mercaptoethane-1-sulfonate. The accelerator can be used in various amounts. Usually, the accelerator is used in an amount of from 0.1 ppm to 1000 ppm, preferably from 1 ppm to 50 ppm, and more preferably from 5 ppm to 20 ppm.

Any compound capable of inhibiting the rate of metal plating can be used as an inhibitor in the plating composition of the present invention. Suitable inhibitors include, but are not limited to, polypropylene glycol copolymers and polyethylene glycol copolymers, including ethylene oxide-propylene oxide ("EO/PO") copolymers and butanol-ethylene oxide-rings. Oxypropane copolymer. The weight average molecular weight of the inhibitor may range from 800 to 15,000, preferably from 1000 to 15,000. When the inhibitor is used, it is preferably present in an amount ranging from 0.5 g/L to 15 g/L, and more preferably from 1 g/L to 5 g/L, by weight of the composition. The leveling agent of the present invention may also have an ability to act as an inhibitor Features.

Usually, the reaction product has a number average molecular weight (Mn) of from 200 to 100,000, typically from 300 to 50,000, preferably from 500 to 30,000, although reaction products having other Mn values may be used. The weight average molecular weight (Mw) value of the reaction product may range from 1000 to 50,000, typically from 5,000 to 30,000, although other Mw values may be used.

The amount of the reaction product used in the copper plating bath for plating the photoresist-defined features (preferably copper pillars) may range from 0.25 ppm to 20 ppm based on the total weight of the plating bath. Preferably, it is from 0.25 ppm to 10 ppm, more preferably from 0.25 ppm to 5 ppm.

The electroplating composition can be prepared by combining the components in any order. Preferably, the inorganic component is first added to the bath container, such as a source of metal ions, water, an electrolyte, and optionally a source of halide ions, followed by the addition of organic components such as reaction products, accelerators, inhibitors, and any Other organic components.

The copper plating bath may optionally contain a conventional leveling agent, with the proviso that the leveling agent does not substantially impair the structure and function of the copper column. The leveling agent can be disclosed in U.S. Patent No. 6, 610, 192 to Steps et al., U.S. Patent No. 7,128,822 to Wang et al., U.S. Patent No. 7,374,652 to Hayashi et al., and U.S. Patent No. 6,800,188 to Hagiwara et al. Leveling agent. Preferably, however, the leveling agent is removed from the bath.

Typically, the plating composition can be used at any temperature from 10 ° C to 65 ° C or higher. Preferably, the plating composition has a temperature of from 15 ° C to 50 ° C and more preferably from 20 ° C to 40 ° C.

Generally, the copper plating bath is agitated during use. Can make Any suitable agitation method is employed and the methods are well known in the art. Suitable agitation methods include, but are not limited to, air injection, workpiece agitation, and impact.

Typically, the substrate is plated by contacting the substrate with a plating bath. The substrate typically acts as a cathode. The plating bath contains an anode which may be soluble or insoluble. An electric potential is applied to the electrodes. The current density may range from 0.25 ASD to 40 ASD, preferably from 1 ASD to 20 ASD, more preferably from 4 ASD to 18 ASD.

While the method of the present invention can be used to plate features defined by photoresists, such as pillars, bond pads, and wire space features, the method is described in the context of plating a copper post that is a preferred feature of the present invention. Typically, a copper pillar can be formed by first depositing a conductive seed layer on a substrate such as a semiconductor wafer or die. The substrate is then coated and imaged with a photoresist material to selectively expose the photoresist layer to radiation such as UV radiation. The photoresist layer can be applied to the surface of the semiconductor wafer using conventional methods known in the art. The thickness of the photoresist layer can vary depending on the height of the feature. Typically, the thickness is in the range of 1 μm to 250 μm. A patterned mask is applied to the surface of the photoresist layer. The photoresist layer can be a positive or negative photoresist. When the photoresist is a positive type, the photoresist portion exposed to the radiation is removed with a developer such as an alkaline developer. A pattern of a plurality of apertures is formed on the surface that extends all the way down to the seed layer on the substrate or die. The distance between the columns may range from 20 μm to 400 μm. Preferably, the pitch may range from 40 μm to 250 μm. The diameter of the orifice can vary depending on the diameter of the feature. The diameter of the orifice may range from 2 μm to 200 μm, typically from 10 μm to 75 μm. The entire structure can then be placed in a copper electroplating bath containing one or more of the reaction products of the present invention. Electroplating to have a substantially flat The top copper pillar fills at least a portion of each orifice. The plating is vertically filled and is not horizontally plated or overfilled. The entire structure with copper posts is then transferred to a bath containing solder (such as tin solder or tin alloy solder, such as tin/silver or tin/lead alloy), and the solder bumps are plated onto each of the copper pillars. A flat surface to fill the aperture portion. The remaining photoresist is removed by conventional means known in the art, leaving an array of copper pillars with solder bumps on the die. The remaining seed layers that are not covered by the pillars are removed by etching methods well known in the art. A copper post with solder bumps is placed in contact with a metal contact of a substrate such as a printed circuit board, another wafer or die or an insert that can be made of an organic laminate, tantalum or glass. The solder bumps are heated using conventional methods known in the art to reflow the solder and connect the copper posts to the metal contacts of the substrate. A conventional reflow method for reflowing solder bumps can be used. An example of a reflow oven is the FALCON 8500 tool from Sikiama International, Inc., which contains 5 heating zones and 2 cooling zones. The reflow cycle can be in the range of 1-5. The copper posts physically and electrically contact the metal contacts of the substrate. The primer material can then be injected to fill the space between the die, the post and the substrate. Conventional primers well known in the art can be used.

1 and 2 are SEMs of a copper pillar of the present invention having a cylindrical shape with a substrate for plating a solder bump, a side surface, and a substantially flat top. During reflow, the solder is melted to obtain a smooth surface. If the post is too bulged during reflow, the solder may melt and flow away from the sides of the post, and there is not enough solder on the top of the post for the subsequent bonding step. If the column is too concave, as shown in Figure 3, the material left from the copper bath used to plate the pillars can remain in the top of the recess and contaminate the solder bath, thereby shortening the life of the solder bath .

In order to provide metal contacts and bonds between the copper pillars and the semiconductor grains during electroplating of the pillars, the under bump metallization layers, typically composed of materials such as titanium, titanium-tungsten or chromium, utilize known in the art. Conventional methods are deposited on the grains. Alternatively, a metal seed layer, such as a copper seed layer, can be deposited over the semiconductor die to provide a metal bond between the copper post and the semiconductor die. After removing the photoresist layer from the die, all portions of the under bump metallization layer or seed layer are removed, except for the portion below the pillar. Conventional methods known in the art can be used to remove the seed layer.

Although the height of the copper pillars may vary, typically, the height thereof ranges from 1 μm to 200 μm, preferably from 5 μm to 50 μm, more preferably from 15 μm to 50 μm, and even more preferably from 15 μm to 40 μm. The diameter of the copper column can also vary. Typically, the diameter of the copper pillars is from 2 μm to 200 μm, preferably from 10 μm to 75 μm, more preferably from 20 μm to 25 μm.

The copper electroplating method and bath provide features defined by a copper photoresist having a substantially uniform morphology and substantially free of nodules. The copper posts and bond pads have a substantially flat profile. The copper electroplating bath and method are capable of achieving an average TIR% to achieve the desired morphology and a balance between average TIR% and WID%.

The following examples are intended to further illustrate the invention but are not intended to limit the scope thereof.

Example 1

In a 125 mL round bottom three-necked flask equipped with a condenser and a thermometer, 100 mmol of 2-(2-aminoethyl)pyridine and 20 mL of DI water were added. The mixture was heated to 80 ° C, followed by dropwise addition of 100 mmol of 1,4-butanediol diglycidyl ether. The resulting mixture was heated to about 4 hours using an oil bath set at 90 °C. At the time, and then stirred at room temperature for another 4 hours. The reaction product (Reaction Product 1) solution was used without further purification.

Example 2

In a 125 mL round bottom three-necked flask equipped with a condenser and a thermometer, 100 mmol of 2-(2-methylaminoethyl)pyridine and 20 mL of DI water were added. The mixture was heated to 80 ° C, followed by dropwise addition of 100 mmol of 1,4-butanediol diglycidyl ether. The resulting mixture was heated using an oil bath set at 90 ° C for about 4 hours, and then stirred at room temperature for another 4 hours. The reaction product was diluted with water, transferred to a storage vessel and used without further purification.

Example 3

In a 125 mL round bottom three-necked flask equipped with a condenser and a thermometer, 90 mmol of 2-benzylaminopyridine and 10 mmol of 2-(2-aminoethyl)pyridine were added to 20 mL of DI water and 6 ml of 50% sulfuric acid. In the mixture. The resulting mixture was heated to 80 ° C, followed by dropwise addition of 100 mmol of 1,4-butanediol diglycidyl ether. The reaction mixture was heated using an oil bath set at 90 ° C for about 4 hours and then stirred at room temperature for a further 4 hours. The reaction product (Reaction Product 3) solution was used without further purification.

Example 4

In a 125 mL round bottom three-necked flask equipped with a condenser and a thermometer, 100 mmol of 2-(2-aminoethyl)pyridine and 20 mL of DI water were added. The mixture was heated to 70 ° C, followed by the dropwise addition of 80 mmol of 1,2,7,8-dicyclooxyoctane. The resulting mixture was heated using an oil bath set at 80 ° C for about 4 hours, and then stirred at room temperature for another 4 hours. The reaction product (Reaction Product 4) was diluted with acidified water and used without further purification.

Example 5

The aqueous acid copper plating bath was prepared by combining 40 g/L copper ion from copper sulfate pentahydrate, 140 g/L sulfuric acid, 50 ppm chloride ion, 5 ppm accelerator, and 2 g/L inhibitor. The accelerator is bis(sodium-sulfopropyl) disulfide. The inhibitor is an EO/PO copolymer having a weight average molecular weight of about 1,000 and a terminal hydroxyl group. The plating bath also contained 1 ppm of the reaction product 1 from Example 1. The pH of the bath is less than 1.

A 300 mm(R) wafer section (available from IMAT, Inc., Vancouver, WA, USA) having a patterned photoresist of 50 [mu]m thickness and a plurality of orifices was immersed in a copper electroplating bath. The anode is a soluble copper electrode. The wafer and anode are connected to a rectifier and a copper post is electroplated onto the exposed seed layer at the bottom of the orifice. The orifice diameter was 50 μm. The current density during plating was 9 ASD, and the temperature of the copper plating bath was at 25 °C. After electroplating, the remaining photoresist was then stripped with a BPR photostripper base solution available from the Dow Chemical Company, leaving a copper column array on the wafer. Then analyze the shape of the copper column. The height of the column and TIR were measured using an optical white light LEICA DCM 3D microscope. TIR% is determined by the following equation: TIR% = [height _center - height _edge ] / height _max × 100, TIR = height _center - height _edge

The average TIR% of the eight bars was also determined as shown in the table.

The WID% of the column array was measured with an optical white LEICA DCM 3D microscope and the following equation: WID% = 1/2 x [(height _max - height _min ) / height _avg ] x 100

WID% was 7.9% and the average TIR% was 7.7%. The surface of the column is smooth and free of nodules. The copper electroplating bath containing the reaction product 1 was plated with a good copper column. Figure 1 is a 300X AMRAY SEM image of one of the columns plated on a seed layer and analyzed by optical microscopy. The surface morphology of the column is smooth and the column has a substantially flat surface. The estimated TIR% of the column is about 0-5%.

Example 6

A tantalum wafer section (available from IMAT, Inc., Vancouver, WA) having a patterned photoresist of 50 [mu]m thickness and a plurality of orifices was immersed in the copper electroplating bath of Example 5. The anode is a soluble copper electrode. The wafer and anode are connected to a rectifier and a copper post is electroplated onto the exposed seed layer at the bottom of the orifice. The current density during plating was 9 ASD, and the temperature of the copper plating bath was at room temperature.

After the plating of the wafer with a copper pillar, followed by the top of the copper pillar tin / silver solder using SOLDERON ^TM BP TS6000 tin / silver electroless plating solution (available from Dow Chemical Company, Midland, Michigan (Midland, MI )) Electroplating. The extent to which the solder is plated to the photoresist in each orifice. The photoresist is then stripped using an alkaline stripper. The wafer was then reflowed using a Falcon 8500 tool from Sikama International, Inc. with 5 heating zones and 2 cooling zones, using a temperature of 140/190/230/230/260 °C for a residence time of 30 seconds. The conveyor belt rate was 100 cm/min and the nitrogen flow rate was 40 cubic feet per hour (approximately 1.13 cubic meters per hour). ALPA 100-40 flux (Cookson Electronics, Jersey City, NJ, USA) is a flux used in reflow. Perform a reflow cycle. After reflow, eight columns were taken using FIB-SEM to take a cross section and the gap between the copper post and the solder was examined. No voids were observed at the interface between the solder and the copper posts.

Example 7

The copper pillar plating method as described in Example 5 was repeated except that the tantalum wafer had a plurality of orifices of patterned photoresist 40 μm thick and 20 μm in diameter (available from IMAT, Inc., Vancouver, Washington). The reaction product 1 was contained in a copper plating bath in an amount of 10 ppm and plating was carried out at 4.5 ASD. Analyze the shape of the eight copper columns.

The column array had a WID% of 5% and an average TIR% of 11.6%. column The surface appears smooth and free of nodules. The post has a slight bulge but is suitable for receiving solder bumps.

Example 8

The copper pillar plating method as described in Example 5 was repeated except that the reaction product 1 was contained in the copper plating bath in an amount of 10 ppm. Analyze the shape of the eight columns.

WID% was 7.1% and the average TIR% was 7.1%. The column surface appears smooth and free of nodules. The post has a sufficiently flat top for receiving solder bumps.

Example 9

The copper column plating method as described in Example 5 was repeated except that the reaction product 1 was contained in the copper plating bath in an amount of 0.25 ppm, the copper plating bath was at a temperature of 30 ° C, and the copper was plated at 14 ASD. The current density is carried out. Table 4 below discloses the data obtained from the analysis of the 300 mm wafer segment.

The WID% was determined to be 12.2% and the average TIR% was -2.8%. The column morphology is smooth and free of nodules.

Example 10

The copper pillar plating method as described in Example 5 was repeated except that the tantalum wafer had a plurality of orifices of patterned photoresist 40 μm thick and 20 μm in diameter (available from IMAT, Inc., Vancouver, Washington). The reaction product 2 was contained in a copper plating bath in an amount of 1 ppm and plating was carried out at 4.5 ASD. Analyze the shape of the eight copper columns.

WID% is 9% and the average TIR% is 10.4%. The column surface appears smooth and free of nodules. The column is slightly raised but its top is flat enough for receiving solder.

Example 11

The copper pillar plating method as described in Example 5 was repeated except that the tantalum wafer had a patterned photoresist of 50 μm thick and a diameter of 50 μm (available from IMAT, Inc., Vancouver, Washington). The reaction product 3 is contained in the bath instead of the reaction product 1. The reaction product 3 was contained in a copper plating bath in an amount of 10 ppm and plating was carried out at 9 ASD. Analyze the shape of the eight copper columns.

WID% was 8.3% and the average TIR% was 7.4%. The column surface appears smooth and free of nodules. The top of the post is flat enough to receive the solder bumps.

Example 12

The method of Example 6 was repeated except that the reaction product in the copper plating bath was the reaction product 3 of the above Example 3. The top plating copper pillar SOLDERON ^TM BP TS6000 tin / silver electroless plating solution, as described in Example 6 and then the reflow. After reflow, the eight copper pillars were sectioned using FIB-SEM and the gap between the copper pillars and the solder was examined. No voids were observed at the interface between the solder and the copper posts.

Example 13

The copper column plating method as described in Example 5 was repeated except that the reaction product 4 was contained in the bath instead of the reaction product 1, and the copper was plated under 14 ASD. get on. Reaction product 4 was added to the copper bath in an amount of 1 ppm. Analyze the shape of the eight columns.

The WID% was 14.2% and the average TIR% was -5.3%. The column surface appears smooth and free of nodules. Although the column has a very slight depression, the top is generally flat overall. Figure 2 is an SEM of one of the electroplated columns.

Example 14

The procedure of Example 6 was repeated except that the reaction product in the copper plating bath was the reaction product 4 of the above Example 4, and copper plating was carried out at 14 ASD. The top plating copper pillar SOLDERON ^TM BP TS6000 tin / silver electroless plating solution, as described in Example 6 and then the reflow. After reflow, the eight copper pillars were sectioned using FIB-SEM and the gap between the copper pillars and the solder was examined. No voids were observed at the interface between the solder and the copper posts.

Example 15 (comparative)

The copper pillar plating method as described in Example 5 was repeated except that the tantalum wafer had a plurality of orifices of patterned photoresist 40 μm thick and 20 μm in diameter (available from IMAT, Inc., Vancouver, Washington). The unreacted product was contained in a copper bath. The copper electroplating bath has the following composition: 40 g/L copper ion from copper sulfate pentahydrate, 140 g/L sulfuric acid, 50 ppm chloride ion, 5 ppm double (sodium) a sulfopropyl) disulfide and a 2 g/L EO/PO copolymer inhibitor having a terminal hydroxyl group having a weight average molecular weight of about 1,000. The pH of the bath is less than 1. Except for water, no other components are included in the bath. Copper plating was carried out under 9 ASD. Analyze the shape of the eight copper columns.

Although the column appears to have a smooth surface and no nodules, the overall result is poor, WID% exceeds 17%, and the average TIR% is greater than 12%. All of the columns analyzed had a severe ridge top.

Example 16 (comparative)

In a 125 mL round bottom three-necked flask equipped with a condenser and a thermometer, 90 mmol of 2-methylquinolin-4-amine and 10 mmol of 2-(2-aminoethyl)pyridine were added to 20 mL of DI water and 5 ml of 50%. In a mixture of sulfuric acid. The mixture was heated to 80 ° C, followed by dropwise addition of 100 mmol of 1,4-butanediol diglycidyl ether. The resulting mixture was heated using an oil bath set at 95 ° C for about 4 hours, and then stirred at room temperature for another 8 hours. The reaction product (Reaction Product 5-Comparative) was diluted with acidified water and used without further purification.

Example 17 (comparative)

In a 125 mL round bottom three-necked flask equipped with a condenser and a thermometer, 50 mmol of 2-(2-aminoethyl)pyridine and 20 mL of DI water were added. will The mixture was heated to 70 ° C, followed by dropwise addition of 50 mmol of epichlorohydrin. The resulting mixture was heated using an oil bath set at 80 ° C for about 4 hours, and then stirred at room temperature for another 4 hours. The reaction product (reaction product 6-comparative) was diluted with water and used without further purification.

Example 18 (comparative)

The copper column plating method as described in Example 5 was repeated except that the reaction product from Example 16 was compared to the replacement reaction product 1 contained in the bath. Copper plating was carried out under 9 ASD. The reaction product 5--comparison was added to the copper bath in an amount of 1 ppm. Analyze the shape of the eight columns.

Many columns have a rough surface with nodules, and all columns are irregular in shape, and many have a "groove-hole" top, as shown in Figure 3. WID% and TIR% were not determined because the column defects were too large for the surface profiler to accurately read.

Example 19 (comparative)

The procedure of Example 5 was repeated except that the reaction product-5 was added to the copper bath in an amount of 10 ppm instead of the reaction product 1. The results were substantially the same as in Example 18, and most of the columns had rough surfaces and all had a concave or groove-hole top. The surface profiler cannot accurately read the column.

Example 20 (comparative)

The copper column plating method as described in Example 5 was repeated except that the reaction product 6 from Comparative Example 17 was used instead of the reaction product 1 in the bath. Copper plating was carried out at 14 ASD. The reaction product 6-comparison was added to the copper bath in an amount of 10 ppm. Analyze the shape of the eight columns.

The column has a smooth surface. The WID% is 12.7% and the average TIR% is -11.3%. All columns have a heavily concave top.

Claims (7)

A method for electroplating a photoresist-defining feature comprising: a) providing a substrate comprising a photoresist layer, wherein the photoresist layer comprises a plurality of apertures; b) providing a copper plating bath, The copper electroplating bath comprises one or more reaction products of one or more pyridylalkylamines of structure (I) and one or more bisepoxides having structure (II): Wherein R ₁ , R ₂ , R ₃ and R _{5 are} independently selected from hydrogen, (C ₁ -C ₆ )alkyl, (C ₁ -C ₆ )alkyl (C ₆ -C ₁₀ )aryl, -NR ₆ R ₇ and R ₈ -NR ₆ R ₇ , wherein the restriction condition is that at least one of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ is R ₈ -NR ₆ R ₇ ; R ₈ is (C ₁ -C ₁₀ ) a hydrocarbon group; R ₆ and R _{7 are} independently selected from hydrogen, (C ₁ -C ₆ )alkyl, (C ₆ -C ₁₀ )aryl, (C ₁ -C ₆ )alkyl (C ₆ -C ₁₀ )Aryl; Wherein R ₉ and R _{10 are} independently selected from hydrogen and (C ₁ -C ₄ )alkyl, A=O((CR ₁₁ R ₁₂ ) _m O) _n or (CH ₂ ) _y , each R ₁₁ and R ₁₂ Independently selected from hydrogen, methyl or hydroxy, m = 1-6, n =1-20 and y =0-6, and when y =0, A is a chemical bond; an electrolyte; one or more accelerators; Or a plurality of inhibitors; c) immersing said substrate comprising said photoresist layer having said plurality of orifices in said copper electroplating bath; and d) plating in said plurality of orifices A plurality of features defined by a plurality of photoresists, the plurality of photoresists defining features comprising an average TIR% of from -5% to +12%. The method of claim 1, wherein the plurality of photoresists define a feature having a WID% of from 5% to 14%. The method of claim 1, wherein the diepoxide has the formula: Wherein R ₉ and R _{10 are} independently selected from hydrogen and (C ₁ -C ₄ )alkyl, and R ₁₁ and R _{12 are} selected from hydrogen, methyl or hydroxy, m = 1-6 and n =1. The method of claim 1, wherein the one or more reaction products are present in the copper plating bath in an amount of from 0.25 ppm to 20 ppm. The method of claim 1, wherein the one or more photoresists define features selected from the group consisting of pillars, bond pads, and line space features. The method of claim 1, wherein the current density is from 0.25 ASD to 40 ASD. A photoresist-defined array of features on a substrate comprising an average TIR% of from -5% to +12% and a WID% of from 5% to 14%.